Method of preventing explosions in subterranean hollows.



l69-45a OR 9441977 SR- A. B. STEPFENS.

METHOD OF PREVENTING EXPLOSIONS IN SUBTBRBANEAN HOLLOWS.

APPLIOATION FILED rm. 24, 1909.

944,977, Patented D60. 28, 1909.

3 SHEETS-SHEET 1.

m EM 7 ML A. B. STEFFENS. METHOD OF PREVENTING EXPLOSIONS IN SUBTERRANEAN HOLLOWS.

Patented Dec. 28, 1909.

3 SHEETS-SHEET 2.

APPLICATION FILED FEB. 24, 1909.

A. B. STEPFENS.

METHOD OF PREVENTING EXPLOSIONS IN SUBTBRBANBAN HOLLOWS.

APPLICATION FILED T31R24, 1909.

944,977. Patented Dec.28,1909. I a sums-sum 3.

GLASS i6-FlRE EXTINGUlSl-lEliS "snrrn STATES ALFRED B. STEFFENS, OF CHICAGO, ILLINOIS.

METHOD OF PREVENTING EXPLOSIONS IN SUBTERRANEAN HOLLOWS.

Specification of Letters Patent.

Patented Dec. 28, 1909.

To all whom it may concern:

Be it known that I, ALFRED B. STErFnNs, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Methods of Preventing Explosions in Subterranean Hollows; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention has for its object to provide a novel method of preventing explosions in mines, tunnels and other underground cavities, and consists in the novel features hereinafter fully described and claimed.

My invention relates more particularly to the prevention of explosions in coal mines.

I11 mining coal the usual method of procedure consists in first excavating laterally from the shaft what are known as the main entries. From the main entries are run what are known as cross-entries and from the cross-entries the excavation is carried into rooms. Each of these rooms of which a large number are cut parallel with each other are divided off by partition walls of coal and are connected with each other by means of cross-cuts or openings in the partition walls. The said rooms and entries terminate in a wall of coal upon which operations are concentrated and which are generally known as faces. The workin ends of said rooms and entries are very difl icult of ventilation. In the operation of mining coal it is customary at the present time to drill holes into the end wall of the room and entry into which subsequently powder or other explosive is inserted and the coal blasted out. In the operation of cutting, drilling, blasting and the operations of removing the loose coal from therooms and entries a great deal of very fine coal dust is produced and this is maintained in constant suspension in the air. In some mines in addition to the coal dust which is a constant menace, more or less inflammable gas is found, but which being lighter than air usually collects adjacent the ceiling of the rooms and entries. The said gas becoming admixed with air constitutes an explosive mixture. In blasting, the explosive is inserted as far back in the drillholes as possible and the mouth of the hole is then rammed full of clay or other suitable material, and is exploded by means of fuses, squibs electricity or in any other well known manner. Explosions in such mines are caused mainly by what are known as windy shots, that is to say, a shot which instead of shattering the mass of coal, shoots out of the drill-hole in the same manner as out of the mouth of a cannon. It is well known that a jet of flame emitted by a powder blast is intensely hot, and this heat and the concussion communicated to the mixture of air and coal dust or gas or both causes the same to explode. When once an explosion takes place it is frequently communicated from room to room and entries, and results in great damage and frequently in the utter destruction of the mine as well as loss of life. Furthermore, the blasting of the coal fre quently causes ignition thereof, and to prevent the spread of fire from this cause, men are employed in many mines whose sole duty it is to follow up the shot firing for the purpose of extinguishing any blaze in the coal. It happens however, at times that an oversight is made and as the shot firing is the final operation of the day, any fire which may start is apt to spread during the idle hours and in gaining suflicient head-way causes a suificiently intense heat to generate and ignite gases and the coal dust suspended in air, so that explosions result which in turn frequently cause damage or destruction of some or all parts of the mine.

The greatest menace in most mines is the coal dust suspended in air. The dry dust lying upon the floor of the mine is constantly kicked up by the mules, passage of cars and other commotion due to operation, but this mixture does not ignite from the miners lamps for the reason that the heat of the latter is insuflicient to cause ignition. The time of greatest danger is during the shot firing, and almost the sole source of danger is the windy shot which produces a flame of sufliciently intense heat and concussion to cause ignition of the coal dust or gas or both suspendedin or mixed with the am My present invention has for its object to provide means whereby not only explosions due to blown out or so-called windy shots r eI 1 tgyrixgt gmwhich.winwcondensafipg will prgiiipitate said dust andby. causing an outward current froin the room or entry cause accummulated gases to be ejected into the ventilating current, or will in any event disturb and destroy the stratification of the gas and render the resulting mixture of steam, air and gas inexplosive. The said steam is introduced prior to the firing of the shots and is preferably discontinued immediately after the shots shall have been fired, the duration of introduction of steam being governed by local conditions.

My said method may be carried out in any suitable manner, and by any suitable apparatus, an example of which is illustrated in the accompanying drawings in which Figure 1 is a fragmentary plan view of a mine showing the main and crossentries and rooms, and showing pipes extending through the latter and equipped adjacent the dead ends of said rooms with suitable nozzles for the discharge of steam adjacent the said dead ends thereof. Fig. 2: is a fragmentary detail view showing a suitable arrangement of pipes for the distribution of steam from a main into gradually smaller supply and discharge pipes respectively. Fig. 3 is a fragmentary vertical section of the dead end wall of the room showing the relative positions of the drill holes. Fig. t is a detail view of a discharge pipe or nozzle suited to the purpose. Fig. 5 is a vertical transverse section of a room or entry showing the operating wall thereof in elevation. Fig. 6 is a cross section of the nozzle shown in Fig. 4.

My said method consists preferably in introducing the steam at a point adjacent the floor of the room or entry and adjacent the operating face or dead end thereof and extending preferably the entire width of the same, the jets of steam emitted being directed vertically upwardly substantially parallel with the dead end or operating wall at a distance therefrom. Other jets are ejected a11- gularly against the operating face and outwardly from the same. The steam impinging upon the roof is deflected downward, condenses and during condensation will fall, thereby precipitating with it the coal dust held in suspension, and which is enveloped and moistened by the condensing steam. The said upwardly and angularly directed jets will form a dense curtain of partially condensed steam in front of the dead end of the room which is substantially impenetrable to flame, and acts as a preventive of combustion.

The steam projected against the roof of the room will obviously disturb and displace the gases collected adjacentthe roof, and throw the same toward the mouth of the room and cause it to commingle with the steam and lower air strata, and by reason of such gas commingling with steam in greater volume it becomes incombustible.

In mines where gas is liberated in such volume as to constitute a danger even greater than that from coal dust explosion, the discharge nozzle is preferably disposed adjacent the roof and as close to the working face as possible. The perforations therein are so disposed as to direct jets of steam downwardly parallel with the working face in order to form the steam curtain and another set of perforations being so disposed as to project the steam parallel with the roof and toward the mouth of the room, thus blowing the gas out of proximity to the point of blasting. Still other perforations may be provided to project the steam angularly downwardly. Besides effecting prevention of explosion at the working faces the steam thus introduced affords a great many other advantages. Said steam will obviously condense on and brush and cleanse the walls of the room or entry, and the water from condensed steam settling on the floor would moisten the coal dust and refuse to a greater or less extent. Each of said rooms or entries is rendered more habitable and healthy, and is maintained cleaner than is ordinarily the case, especially as the condensation of steam will cause an inrush of fresh air to replace the same. Furthermore, fires caused by the blasting usually occur in the heap of shattered coal thrown out by the blast, and a jet of steam directed upon the burning coal effectually prevents combustion and thereby extinguishes the fire.

The steam main A of suitable diameter may enter the mine either through the hoisting shaft or the air shaft and connects with the horizontal mains B in the main entry of the mine. A valve C preferably located above ground controls the supply to the main A and valves D disposed adjacent the connections of the mains B with the main A control the former. From the mains B the supply pipes E branch off into the cross-entries and are controlled by valves F disposed adjacent their connection with the mains B. Discharge pipes G extend from the supply pipes E into the rooms and terminate a short distance from the dead end walls or working faces of the latter.

mass ESQ-FIRE EXTINGUISHERS,

Valves H are interposed in said discharge pipes adjacent their connections with the supply pipes, and other valves I are interposed in said pipes at a suitable distance from the free ends thereof.

Mounted upon the free ends of the discharge pipes are crosspipes J each of which is provided with a plurality of rows of perforations through which steam is discharged upwardly, angularly or horizontally or in desired directions adjacent to the working face of the room or entry. Said cross-pipes I term nozzles and these may be of any desired construction suitable to the purpose.

The respective sizes of the mains, supply and discharge pipes may be determined by persons skilled in the art of steam distribution as may also the manner of suitably supporting the pipes and the manner of fitting extensions thereto as the working of the mine progresses.

In the operation of the system it is intended that before the shot firer operates in the rooms the valves I shall be closed and thereafter upon signal the valve C shall be opened. A few of the valves I, preferably in the rooms farthest removed from the shaft shall then be opened to permit escape of air and again closed after the steam begins to be discharged. The shot firer then proceeds to explode the powder charges in the first room or entry and after lighting his time fuses runs back and either he or an assistant opens the valve I and then passes through one of the openings M into the next room or entry. The time of the blast will be determined by the length of fuses, but we will assume that it occurs two minutes after ignition ofthe fuses. During the said two minutes the steam ejected will have filled the dead end portion of the room thereby producing a curtain or blanket of what may be termed a dense fog. The direction of flow or expansion of this curtain will obviously be toward .the mouth of the room and, hence, away from the point at which the blast occurs. This wet steam will carry with it the suspended coal dust and any accumulated gases. The shot firer or his assistant closes the valve I or H shortly after the blast. In addition to clearing the atmosphere in the rooms and entries the steam will saturate the air with moisture and the condensed steam precipitated upon the floor and collecting on the walls and roof will by exaporation increase the humidity of the air between the intervals of introduction of the steam. This operation is repeated in each room and entry and the engineer is then given the signal to close the valve C. The valves H and I which may have been closed are then reopened. Thus after all operators have left the mine the pipe system may be open throughout and in the event of an alarm of fire during the idle hours the engineer may, by opening the valve C flood the whole mine with steam which would serve to extinguish or check a tire and prevent the occurrence of any explosions.

F or the purpose of additional fire protection the mains and supply pipes in the entries are preferably equipped with pet cocks at suitable intervals whlch would all be opened after the blasting operations have been completed and the valve C closed.

In the mines in which pneumatic tools are used the pipe system supplying compressed air may be converted to the distribution of the steam by disconnecting the tool hose and mounting the nozzle. Thus a single pipe system may serve two functions especially as the operation of the pneumatic tools ceases before my method is carried out.

Steam is a gaseous non-combustible fluid or vapor and is on account of cheapness of production best fitted for my purpose, but I desire it to be understood that any other gaseous non-combustible fluid suited to the purpose may be employed without departing from the spirit of my invention.

In the foregoing specification all reference to the prevention of explosions will be understood to mean only such explosions as may result from the combustion of inflammable gases or coal dust or both found in mines or other subterranean hollows but should not be construed to include the ex plosive used in blasting nor explosions which might result from high pressure of confined fluids bursting their confines.

I claim as my invention:

1. A method of preventing explosions in subterranean hollows when blasting a wall thereof which consists in projecting in front of the wall being blasted, non-combustible fluid under pressure to form a cloud in front of and in close proximity to said wall and continuing such projection during an interval beginning before the explosion of the blasting charge and terminating after the latter. I

2. A method of preventing explosions in subterranean hollows when blasting a wall thereof which consists in projecting in front of the wall being blasted, steam under pressure to form a cloud in front of and in close proximity to said wall and continuing such projection during an interval beginning before the explosion of the blasting charge and terminating after the latter.

A method of preventing explosions in subterranean hollows when blasting a wall thereof consisting in projecting steam under pressure in the form of a cloud in front of and in close proximity to the wall being blasted for a short period immediately preceding and continuing such projection during the blasting and terminating it after a short interval succeeding the blasting.

l. A method of preventing explosions in nating it after a short interval succeeding 20 subterranean hollows when blasting a wall thereof consisting in projecting steam under pressure in the form of a cloud of a height equal to the height of the wall in front of and in close proximity to the Wall being blasted for a short period immediately preceding and continuing such projection during the blasting and terminating it after a short interval succeeding the blastmg.

5. A method of preventing explosions in subterranean hollows when blastinga wall thereof consistin in projecting non-combustible fluid under pressure in the form of a cloud in front of and in close proximity to the wall being blasted for a short period immediately preceding and continuing such projection during the'blasting and termithe blasting.

6. A method of preventing explosions in subterranean hollows when bla'sti'n'gia wall thereof consistingin projecting non-combustible fluid under pressure in the form of a cloud of a height equal to the height of the wall in front of and in close proximity to the wall being blasted for a short period immediately preceding and continuing it after a short interval succeeding the blasting.

In testimony whereof I have signed my name in presence of two subscribing witnesses.

ALFRED B. STEFFENS.

lVitnesses:

M. M. BOYLE, RUDOLPH WM. Lo'rz. 

